SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '23e4be7a5b40fd6543a8fd64e82a5a0b6dedd77f12dd392b9f9b21adee957dc3' 
  AND token = 'm76FpkklLJnliWBPjVIzUXwL0sjhbXcwibnDj//gcqA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}